Biomembrane Division, Industrial Toxicology Research Centre, Mahatma Gandhi Marg, LucknowIndia.
Toxicol Mech Methods. 2005;15(3):211-8. doi: 10.1080/15376520590945630.
The major nonoccupational source of chromium (Cr) for humans is through ingestion with food and water, but its effect on the gut microflora has not been studied. The present study was, therefore, undertaken to investigate the effects of chronic ingestion of potassium dichromate (chromium VI) on the resident gut bacteria of male Wistar rats. A group of rats was kept on drinking water containing 10 ppm chromium VI (Cr [VI]) (called Cr-stressed animals) and the other group was given plain water. After 10 weeks, Lactobacillus, Pseudomonas sp., and Escherichia coli were isolated from the cecum of the rats and various studies were performed. The most significant findings of the present study were the stimulation of growth of facultative gut bacteria from the Cr-stressed rats and the significant increase of growth even in the presence of lower concentrations of Cr. Furthermore, the capacity to reduce Cr (VI) was significantly decreased along with the increased tolerance of the bacteria to Cr (higher minimum inhibitory concentration [MIC] values), which was associated with the development of antibiotic resistance. The effects were most marked with the Pseudomonas sp. and least with the E. coli. The antibiotic resistance developed with the Lactobacillus may be a blessing in disguise, because the bacteria may continue to provide benefits even in patients given antibiotic therapy. The gut bacteria thus provide the first line of defense to the body by converting toxic Cr (VI) to a less toxic Cr (III) and may act as a prebiotic.
人类摄入铬（Cr）的主要非职业来源是通过食物和水，但其对肠道微生物群的影响尚未得到研究。因此，本研究旨在调查长期摄入重铬酸钾（Cr VI）对雄性 Wistar 大鼠肠道常驻细菌的影响。一组大鼠饮用含有 10ppm 六价铬（Cr [VI]）的水（称为 Cr 应激动物），另一组给予普通水。10 周后，从大鼠盲肠中分离出乳酸菌、假单胞菌和大肠杆菌，并进行了各种研究。本研究的最重要发现是，应激 Cr 的大鼠肠道兼性细菌的生长得到了刺激，即使在较低 Cr 浓度下，其生长也显著增加。此外，还原 Cr（VI）的能力显著下降，同时细菌对 Cr 的耐受性增加（MIC 值更高），这与抗生素耐药性的发展有关。假单胞菌的影响最为显著，大肠杆菌的影响最小。与乳酸菌一起产生的抗生素耐药性可能是因祸得福，因为即使给接受抗生素治疗的患者服用，这些细菌仍可能继续提供益处。肠道细菌通过将有毒的 Cr（VI）转化为毒性较小的 Cr（III）来为身体提供第一道防线，并可能起到益生元的作用。
